1. Field of the Invention
The present invention generally relates to a wireless transceiver, more particularly, to a wireless transceiver with an expandable antenna.
2. Description of Related Art
A series of technological breakthroughs in recent years have lead to the rapid development of wireless communication techniques. The appearance of wireless wide-band network, wireless voice communication and wireless broadcast points to the significant advancement and variety of wireless communication techniques now available. In everyday life, people buy products, for example, cellular phones, portable televisions, radios and walkie-talkies, with wireless transceiver function so as to access the electromagnetic signal in surrounding space. All these products have one common feature, they must have an antenna for receiving and transmitting electromagnetic signal.
FIG. 1 is a block diagram of a conventional wireless transceiver with a single antenna. As shown in FIG. 1, the wireless transceiver 100 with a single antenna includes an antenna 110, a receiver 120, a transmitter 130 and a coupler 140. A first signal terminal 141 of the coupler 140 is coupled to the receiver 120, a second signal terminal 142 of the coupler 140 is coupled to the transmitter 130, and a third signal terminal 143 of the coupler 140 is coupled to the antenna 110. As a whole, the wireless transceiver 100 receives and transmits an electromagnetic signal through the antenna 110, and the coupler 140 is used to redirect the signal. In other words, when the antenna 110 receives an electromagnetic signal from surrounding space, the electromagnetic signal is delivered to the third signal terminal 143 of the coupler 140. At this time, the coupler 140 couples the electromagnetic signal received by the third signal terminal 143 to the first signal terminal 141 so that the receiver 120 can receive the electromagnetic signal. Similarly, after the transmitter 130 outputs a radio-frequency signal, the radio-frequency signal is delivered to the second signal terminal 142 of the coupler 140. Therefore, the coupler 140 couples the radio-frequency signal received by the second signal terminal 142 to the third signal terminal 143, and the radio-frequency signal is transmitted to surrounding space through the antenna 110.
It should be noted that the circuit for operating the wireless transceiver 100 with a single antenna is more complicated. Because the device needs to use the only antenna for transmitting and receiving signals, a complicated circuit design is required to boost the selectivity of the wireless transceiver 100 so as to prevent intermediation distortion on the sensitivity of the received signal due to inter-mediation distortion.
FIG. 2 is a block diagram of a conventional wireless transceiver with two antennas. As shown in FIG. 2, the wireless transceiver 200 with two antennas includes an antenna 210, an antenna 220, a receiver 230 and a transmitter 240. The antenna 210 is coupled to the receiver 230 and the antenna 220 is coupled to the transmitter 240. As a whole, the wireless transceiver 200 with two antennas uses the antenna 210 to receive the electromagnetic signal and uses the antenna 220 to transmit the radio-frequency signal. Therefore, the wireless transceiver 200 with two antennas can lower the effect of intermediation distortion on sensitivity, and circuit design can be simplified. However, the transceiver 200 must install both antennas 210 and 220 simultaneously and there are no other options in its operation.
Accordingly, each of the wireless transceivers 100 and 200 has its merits and demerits. Therefore, when a transceiver can have single-antenna and two-antenna characteristics simultaneously so that a user can choose the mode to operate, the transceiver is more useful and has more market worth.